Embodiments of this disclosure relate generally to lighting systems, and more particularly, to an interior illumination and lighting system for passenger cabins in airplanes using micro lens array optics.
In the past, conventional passenger aircraft illumination systems may have used fluorescent and incandescent light sources. However, light emitting diode (LED) based lighting systems may offer several advantages over such conventional systems. These may include smaller source size, lower electrical power consumption, lower weight, and longer operating lifetimes. Thus, presently, many passenger cabins may use illumination systems based on LEDs.
Typical airplane cabin architecture use elongated shapes arranged longitudinally in a manner of continuous strings. It is desirable in the general cabin lighting to have a uniform illumination of the architectural elements. Existing general lighting systems found in the aircraft main cabin may be designed to match architectural features dimensionally in order to achieve a uniform illumination of a desired pattern. Thus existing general lighting applications may make use of continuous linear arrangements of multiple elongated fixtures each of which is based on linear arrays of numerous LEDs.
Aircraft interior lighting usually includes dedicated lighting applications such as task and area lighting. These applications generally utilize mostly spot and flood types of lighting fixtures shining on a specific area or isolated target. Another type of lighting applications is feature lighting. These applications often require complex illumination patterns or close match between the light beam shape and illumination target. Both dedicated and feature lighting may use single LED designs as well as arrays of plural LEDs depending on specific function of the fixture.
All cabin lighting applications assume certain degree of collection of light radiation from the source and redirection of the light towards the illumination target.
Present designs of LED fixtures used in the aircraft interior illumination provide limited control over the spatial distribution of light, which may result in light radiated in undesired directions. Such unwanted light is usually blocked and therefore lost for the purpose of illumination. This loss of light output may need to be compensated by oversizing the lighting system which may lead to increase in weight, cost and energy consumption. Furthermore, the design based on linear LED array may impose certain limitation on the cabin architecture and may increase costs due to the dimensional dependence between a fixture and underlying structural element to which that fixture is attached.
Another implication of the limited control over spatial distribution of light may be inadequate illumination pattern such as uneven light level, dark and hot spots, superfluous illumination. This inadequacy may be especially detrimental for the dedicated and feature lighting applications. One prominent example is a passenger reading light that produces excessively wide light cone that may encroach in to other passengers' space.
Therefore, it would be desirable to provide a system and method that allows for better utilization of a light output produced by a LED source.